Non Bacterial Facial Infections CSU Lecture (1)

Non-Bacterial Facial Infections

Alex D'jamirze, Oral and Maxillofacial Registrar (NSW/ACT)

Pathogens in Head and Neck Infections

Infections in the head and neck can be caused by various types of pathogens, including:

  • Viruses

  • Bacteria

  • Fungi

  • Protozoa

Types of Pathogens

  • Viruses: Pathogens that replicate only inside living cells. Example: Herpes simplex virus.

  • Bacteria: Microscopic organisms, most of which are harmless. Example: Escherichia coli.

  • Fungi: Includes yeasts, filamentous organisms, and dermatophytes. Example: Candida species.

  • Protozoa: Unicellular organisms that can cause infections, typically found in specific environments.

Characteristics of Pathogens

Pathogen Type

Cells

Diameter (μm)

Nucleic Acid

Type of Nucleus

Ribosomes

Mitochondria

Outer Surface

Duplication Method

Viruses

No

1

Either DNA or RNA

None

Absent

Protein capsid

Not binary fission

Bacteria

Yes

0.02 - 0.2

Both

Prokaryotic

70S

Absent

Rigid wall

Binary fission

Fungi

Yes

1 - 5 (yeasts)

Both

Eukaryotic

80S

Present

Rigid wall containing chitin

Budding or mitosis

Protozoa

Yes

15-25 (trophozoites)

Both

Eukaryotic

80S

Flexible membrane

Mitosis

Viruses: Virology

Viruses are among the smallest microorganisms and can infect various life forms. They can cause severe oral and orofacial diseases and are highly transmissible.

Unique Features of Viruses

  • Small size (10-100 nm)

  • Consist of a genome made up of either DNA or RNA, but never both

  • Metabolically inactive outside host cells

  • Obligate intracellular parasites, relying on host cell machinery for replication

  • Viral replication occurs in several distinct, stereotypical stages:

    1. Cell entry: Attachment - Virus binds to specific receptors on the host cell.

    2. Cell entry: Penetration - Virus or its genome enters the host cell via various mechanisms (endocytosis, fusion, translocation).

    3. Uncoating - Release of viral nucleic acids from the capsid.

    4. Transcription of viral genome - Viral mRNA directs the assembly of enzymes for replication.

    5. Synthesis of viral components - Includes structural proteins and enzymes for replication.

    6. Assembly - Incorporation of nucleic acid into procapsids.

    7. Release - Via budding or lysis of the host cell.

Classification of Viruses

Viruses can be classified based on their genetic material (DNA or RNA) and whether they have an envelope:

  • DNA viruses: Example viruses include Herpes simplex virus (HSV), Cytomegalovirus (CMV).

  • RNA viruses: Include Influenza virus, Coxsackieviruses.

  • Enveloped viruses: Such as Herpesviruses and Paramyxoviruses.

  • Non-enveloped viruses: Examples include Adenoviruses and Enteroviruses.

Herpes Viruses

The Herpesviridae family includes several important viruses:

  • HSV-1 & HSV-2: Responsible for oral and genital herpes.

  • Varicella-Zoster Virus (VZV): Causes chickenpox and shingles.

  • Epstein-Barr Virus (EBV): Associated with infectious mononucleosis and malignancies.

  • Cytomegalovirus (CMV): Typically affects immunocompromised individuals.

Clinical Features of Herpes Infections

  • Primary HSV Infections: Often manifested as primary herpetic gingivostomatitis, characterized by systemic symptoms like malaise and pyrexia, alongside widespread oral ulceration.

  • Recurrent Infections: Herpes labialis (cold sores) appears on the lips and can present with prodromal symptoms.

Management Strategies

  • Primary HSV Infection: Management revolves around symptomatic relief and antiviral medications like Acyclovir.

  • Recurrent Herpes: Often requires supportive care with topical medications.

Epstein-Barr and Cytomegalovirus

  • Infectious Mononucleosis: Presents with pharyngitis, fever, and lymphadenopathy; mainly diagnosed through blood tests indicating atypical lymphocytes.

  • Oral Hairy Leukoplakia: Associated with EBV; characterized by white patches on the tongue.

Fungal Infections

Notable fungal infections affecting the oral mucosa include Candidiasis, commonly caused by Candida albicans, and other opportunistic infections seen in immunocompromised individuals.

Clinical Features of Candidiasis

  • Pseudomembranous candidiasis: Known as thrush, it presents as white patches that wipe off revealing an erythematous base.

  • Chronic forms: Can include angular cheilitis and denture stomatitis.

Diagnosis and Treatment of Fungal Infections

Diagnosis often involves culture, histopathology, or clinical on examination. First-line treatments include antifungal medications like Fluconazole and Nystatin.

Conclusion

Understanding the diverse pathogens responsible for oral and facial infections—including their characteristics, replication methods, and clinical manifestations—is essential for effective diagnosis and management in oral and maxillofacial health.